Fluidized bed process

ABSTRACT

A fluidized bed process for the drying and granulation of a 50 per cent by weight aqueous solution of ammonium sulphate is carried out in a container having a conical bottom portion in which a gas is introduced, the conical bottom portion reducing the velocity of gas flowing upward therein from about 7 to 10 to about 4 to 6 feet per second to control the generation of dust.

United States Patent 119 Ganiaris FLUIDIZED BED PROCESS [75] Inventor:Neophytos Ganiaris, Riverdale, NY.

[73] Assignee: Struthers Scientific and International Corporation, NewYork, NY.

22 Filed: June 6,1972

211 App]. No.1 260,147

[30] Foreign Application Priority Data June 18, 1971 Great Britain28,756/71 52 us. Cl. 34/10, 159/D1G. 3 [51] Int. Cl. F26b 17/10, F26b3/08 [58] Field oi Search. 159/4 A, 4 CC, 4 VM, DIG. 3; 34/10, 57 R, 57A, 57 D [56] 7 References Cited UNITED STATES PATENTS 3,255,036 6/1966Kramer et al l59/DIG. 3

1 1 Feb. 26, 1974 3,289,732 12/1966 Kotelnikov et a1. 159/D1G. 33,112,220 [2/1963 Heiser, Jr. et a1. 159/DIG. 3

Primary Examiner-Meyer Perlin Assistant Examiner-William C. Anderson 57ABSTRACT A fluidized bed process for the drying and granulation of a 50per cent by weight aqueous solution of ammonium' sulphate is carried outin a container having a conical bottom portion in which a gas isintroduced, the conical bottom portion vreducing the velocity of gasflowing upward therein from about 7 to 10 to about 4 to 6 feet persecond to control the generation of dust.

1 Claim, 1 Drawing Figure 1 I v FLUIDIZED BED PROCESS' BRIEF DESCRIPTIONOF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENT Blower l forcesair through duct 2 through combustion chamber 3 to deliver heated airthrough duct 4 into the bottom 5 of chamber 6. A perforated plate 7 orthe like divides chamber 6 from bottom 5. The lower portion of chamber 6has a conical configuration 8 which substantially doubles the crosssectional area of chamber 6 from plate 7 to the upper cylindricalportion 10 of chamber 6. Gas passes from the upper end of chamber 6.through duct 11.

If operated as a fluidized bed dryer, feed is introduced through pipe 12to 'a spray head 13 into a fluidized bed 14 formed in container 6. Ifthe feed liquid is about 50 per cent solids, the feed will -coatfluidized particles and dry thereon to build larger granules which willfall. downward and be withdrawn as a product through tube 15.

. If the upward average velocity of gas directly about plate 7 is about10 feet per second, the upward average velocity of gas in thecylindrical portion 10 of chamber 6 will be from4 to 6 per second. Thislower gas velocity in bed 14 reduces the generationof dust or fineswhich are carried upward to pass out duct 11. While the fluidized bed 14is generally disposed above cone 8 in the cylindrical portion 10, anysettling of the bed is stabilized as the bed 14 will not settle into thehigher velocity upward gas flow in cone 8.

This invention may be used to provide aggregated or granulated particlesof ammonium sulphate, ferrous sulphate, or ammonium phosphate.

What is claimed is: I

l. The process of providing product granules from an aqueous feedsolution of substantially 50 per cent by weight of ammonium sulphatecomprising the steps of a. passing heated air upward in a fluidizedbed-dryer having a cylindrical body in which air moves upward at a rateof 4 to 6 feet per second and an inward tapering conical lower end inwhich air moves upward at a rate of 7 to 10 feet per second,

b. spraying the aqueous solution of feed into the cylindrical bodyforming a fluidized bed therein in which drying particles aggregateforming product granules which fallfrom the fluidized bed, the'fluidizedbed being stabilized above the faster flowing air in the conical lowerend of the dryer, the slower fluidizing air in the cylindrical bodyreducing dust generation, and

c. removing product granulesfrorn the bottom of the dryer.

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1. The process of providing product granules from an aqueous feedsolution of substantially 50 per cent by weight of ammonium sulphatecomprising the steps of A. PASSING HEATED AIR UPWARD IN A FLUIDIZED BEDDRYER HAVING A CYLINDRICAL BODY IN WHICH AIR MOVES UPWARD AT A RATE OF 4TO 6 FEET PER SECOND AND AN INWARD TAPERING CONICAL LOWER END IN WHICHAIR MOVES UPWARD AT A RATE OF 7 TO 10 FEET PER SECOND, B. SPRAYING THEAQUEOUS SOLUTION OF FEED INTO THE CYLINDRICAL BODY FORMING A FLUIDIZEDBED THEREIN IN WHICH DRYING PARTICLES AGGREGATE FORMING PRODUCT GRANULESWHICH FALL FROM THE FLUIDIZED BED, THE FLUIDIZED BED BEING STABILIZEDABOVE THE FASTER FLOWING AIR IN THE CONICAL LOWER END OF THE DRYER, THESLOWER FLUIDIZING AIR IN THE CYLINDRICAL BODY REDUCING DUST GENERATION,AND C. REMOVING PRODUCT GRANULES FROM THE BOTTOM OF THE DRYER.